The invention relates to a pressure fluid-delivery device comprising
a cylinder
a piston which is arranged to be moved backwards and forwards in the cylinder, and which has an end portion, which together with an adjacent end portion of the cylinder defines a cylinder space, which is arranged to be connected to a receiver for the pressure fluid, where an axial movement of the piston in a first direction relative to the cylinder, hereinafter called forwards, causes a reduction in the cylinder space and a delivery of pressure fluid therefrom to the receiver,
a reservoir for the fluid, and
a seal which is V-shaped in cross section and which is mounted in an annulus between the cylinder and the piston and attempts to prevent a fluid flow out of the cylinder space via the annulus, and which has a bottom portion and two legs which are interconnected via the bottom portion and project away from each other and forwards from the bottom portion, a first leg, in a similar fashion to a check valve, springingly attempting to seal an outlet opening of a channel which communicates with the reservoir in such a manner that the first leg seals the outlet opening when the pressure in the fluid in the cylinder space is greater than the pressure in the fluid in the reservoir, but opens the outlet opening when the pressure in the fluid in the reservoir is greater than the pressure in the fluid in the cylinder space.
A pressure fluid-delivery device of the above-mentioned type is known from EP-B1-0159 236, where the seal is mounted in a circumferential groove provided in the cylinder. The groove is open radially inwards towards the piston, the seal""s first leg facing radially outwards and the seal""s second leg facing radially inwards and constantly abutting sealingly against an adjacent, cylindrical surface of the piston.
Because the groove is provided in the cylinder, its outer diameter has to be correspondingly increased at least at the location of the groove. Furthermore, the channel is arranged in the cylinder in a relatively complicated manner by providing a number of bores which have to be manufactured in separate machining stages.
This results in a pressure-delivery device which is large and expensive to manufacture.
The object of the invention is to provide a pressure-delivery device of the type mentioned in the introduction which is encumbered to a lesser extent by the above-mentioned disadvantages.
In accordance with the object, this invention provides a pressure fluid-delivery device comprising a cylinder, a piston, which is arranged to be moved backwards and forwards in the cylinder, and which has an end portion, which together with an adjacent end portion of the cylinder defines a front cylinder space, where an axial movement of the piston forwards relative to the cylinder causes a reduction in the volume of the cylinder space and a delivery of pressure fluid from this space, a reservoir for the fluid, and a seal which is V-shaped in cross section and which is mounted in an annulus between the cylinder and the piston and attempts to prevent a fluid flow out of the cylinder space via the annulus, and which has a bottom portion and two legs which are interconnected via the bottom portion and project away from each other and forwards from the bottom portion, a first leg, in a similar fashion to a check valve, springingly attempting to seal an outlet opening of a channel which communicates with the reservoir in such a manner that the first leg seals the outlet opening when the pressure in the fluid in the cylinder space is greater than the pressure in the fluid in the reservoir, but opens the outlet opening when the pressure in the fluid in the reservoir is greater than the pressure in the fluid in the cylinder space, characterized in that the seal rests on a forwardly facing, radially outwardly extending surface of the piston, the seal""s first leg projecting slantingly radially inwards and being arranged to come into abutment against an axially extending portion of the piston, and the seal""s second leg projects slantingly radially outwards and is arranged to slide on and constantly to abut against the cylinder surface.